Managing the landscape to optimise pollinator nutrition How can land managers, policymakers and the public helppollinators to meet their nutritional needs in the UKlandscape?

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Living With Environmental Change Policy and Practice Notes

Note No.26 – Insect Pollinators Initiative February 20 16

Photo by Jon Carruthers

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What are the key resources required forthe nutrition of bees?

Bees require both nectar and pollen from flowers:— Bee offspring require large quantities of floral resources

which the adult females gather on many foraging trips. — Plants make floral nectar as a sugary reward to attract

pollinators. Nectar is the main source of energy for beeswhich they need to power flight, to incubate their larvaeand to make wax. It is important because it:– Is the raw ingredient of honey. – Contains amino acids which may be an important

nutritional resource for adult bees and also forhoverflies.

– Contains other compounds which serve a multitude ofpurposes eg anti-microbial activity, deterrence ofunwanted flower visitors, pollinator attraction.

— Pollen carries the plant’s male reproductive cells, andbees need it because it contains proteins, fats, sterols andmicronutrients, which they require to produce eggs, tomature into adults and to develop their flight muscles.Two essential fatty acids, a-linolenic acid and linoleic acid- and the proportions of these - are crucial for supportingbee development and foraging performance.

What challenges do bees face in meetingtheir nutritional needs?

Bees require flowers throughout their active period. Somesolitary bees are active for just a few weeks but honeybeesand bumblebees forage throughout spring and summer, andneed continuous sources of pollen and nectar from a widevariety of flowering plant species:— Bees need pollen from a diverse range of plant species;

honeybee resistance to disease is impaired when they arefed pollen from a single species.

— Flowering crops such as oilseed rape provide a massive,much needed source of both nectar and pollen in theagricultural landscape for bees. However this is a shortlived synchronous burst of food that does not meet theirfull nutritional needs over the season.

— Exposure to pesticides, including via contaminated nectarand pollen, is one potential threat to pollinatorpopulations, but the effects of exposure to multiplepesticides, and impacts on the majority of wild beespecies and their ecological interactions, is still uncertain.

— Intensively-managed cereal and grass monocultures are“deserts” for pollinators, with very scant floral and nestingresources, but field margins and hedgerows in theselandscapes can be important bee habitats if these aremanaged sensitively by allowing flowers to bloomthroughout the season.

— In areas where many honeybee hives are kept there maybe competition with wild bee populations to find nectarand pollen.

— Periods of extreme weather like drought and coldtemperatures put additional stress on bees as theyincrease the need for nectar, prevent foraging and reducesome floral resources.

Insect pollinators are critically important to ecosystems and human wellbeing.By transporting pollen between flowers of the same species they help to assurehealthy wild plant populations and contribute to sustaining yields of many fruit,vegetable, nut and seed crops. In return, pollinators like bees obtain nectar andpollen foods from a wide range of wild, ornamental and crop plant species.Unfortunately there is evidence that pollinators are declining, probably as aresult of multiple environmental threats. Land use change, managementintensification, invasive species, and even climate change, have reduced theabundance and diversity of flowering plants throughout the growing season.This has reduced the availability of pollen and nectar foods for pollinators andthis lack of nutrition makes bees more susceptible to other threats likediseases, parasites and pesticides. Inadequate nutrition is therefore likely to bea major cause of pollinator declines.

Living With Environmental ChangeManaging the landscape to optimise pollinator nutrition

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How do plants vary as sources ofnutrition for pollinators?

The amount and nutritional content of pollen and nectarcan vary between plant species and even betweenindividuals within a species and are affected by a range offactors:— Variation can depend on the time of day, soil type,

competition with other pollinators, and weather conditions(particularly water availability and temperatures).

— Some flowers, like poppies, produce no nectar while others,like bramble flowers, produce a large amount. Someflowers produce large amounts of pollen eg willow.

— The nutritional value of pollen depends on plant speciesand can be affected by plant stressors including drought,temperature, humidity, ozone and other pollutants.

— The protein content of pollen varies. Some species ofplants do offer pollen with the full complement of essentialnutrients, like amino acids, that bees require but generallybees must collect pollen from several species to acquire alltheir essential nutrients.

How can the landscape be improved toprovide better nutrition for domesticatedand wild bee species?

A range of approaches can be beneficial:— Conservation and creation of semi-natural habitats, like

hedgerows that contain flowering plants such as brambles,provide food and nesting sites for pollinators, supporting agreater abundance and diversity. This can be done withoutimpact on agricultural production.

— Several agri-environment schemes have benefits forpollinators, particularly planting of nectar- and pollen-richflower mixes in field margins. The effectiveness of theseschemes depends on the landscape and crop type in whichthey are placed, ie simple versus complex; arable versusgrassland. Therefore, to get value for money the placementof such schemes must be carefully considered.

— Organic and other diversified farming systems of lowermanagement intensity can promote pollinator populationsby increasing wild flower densities and diversity at themargins and centres of fields.

— Some cultivars of agricultural crops provide better andmore abundant nutrition than others. Careful breeding ofplants for traits that produce good crops and also abundantnectar and pollen would improve habitats for bees andother pollinators.

— Developing alternative pollen substitutes that couldprovide sufficient nutrition for domesticated bees duringtimes of dearth would aid beekeepers throughout theworld.

Policy and Practice NotesNote No.26 – Insect Pollinators Initiative February 2016

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Living With Environmental ChangeManaging the landscape to optimise pollinator nutrition

This Policy and Practice Note was written by Geraldine Wright, EileenPower and Jon Carruthers drawing on the Insect Pollinators Initiativeproject: Can bees meet their nutritional needs in the current UKlandscape? The Insect Pollinators Initiative is funded by theBiotechnology and Biological Sciences Research Council, theDepartment for Environment, Food and Rural Affairs, the NaturalEnvironment Research Council, the Scottish Government and theWellcome Trust under the auspices of the LWEC partnership.Useful resources: Insect Pollinators Initiative: http://www.insectpollinatorsinitiative.netAll the Insect Pollinators Initiative notes in the LWEC Policy and PracticeNote series may be found athttp://www.nerc.ac.uk/research/partnerships/lwec/products/ppn/ The British Beekeeping Association: http://www.bbka.org.uk/Reversing Insect Pollinator Declines POSTnote:http://researchbriefings.parliament.uk/ResearchBriefing/Summary/POST-PN-442/

Scheper et al. (2013). Environmental factors driving the effectiveness ofEuropean agri-environmental measures in mitigating pollinator loss - ameta-analysis. Ecology Letters 16: 912-920.http://onlinelibrary.wiley.com/wol1/doi/10.1111/ele.12128/abstractNational Pollinator Strategy:https://www.gov.uk/government/publications/national-pollinator-strategy-for-bees-and-other-pollinators-in-englandBumblebee Conservation Trust: http://bumblebeeconservation.org/Potts et al. (2009). Enhancing pollinator biodiversity in intensivegrasslands. Journal of Applied Ecology 46: 369-379.http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2009.01609.x/fullCountryside Stewardship Manual:https://www.gov.uk/guidance/countryside-stewardship-manualContact: Professor Geraldine Wright email jeri.wright@ncl.ac.uk Series editor: Anne Liddon, Newcastle UniversitySeries coordinator: Jeremy Phillipson, Newcastle University

Further information

Insect Pollinators Initiative

National and local policymakers can help by: — Promoting agri-environment schemes that support pollinators. — Maintaining populations of native deciduous trees in urban and rural landscapes that are sources of nectar and pollen for

many pollinator species such as willow.— Encouraging breeding of crop varieties to produce more nectar and pollen including crops such as oilseed rape.— Including the testing of nectar production in variety trials to inform farmers about making pollinator-friendly choices.— Supporting schemes to help consumers identify products grown with consideration for pollinators.— Reducing destruction of natural habitats with a large diversity of flowering plants and encouraging land reclamation for

native plants.

What actions could help meet pollinators’ nutritional needs?

Land managers can help by:— Joining the Countryside Stewardship agri-environment

scheme which includes payments to farmers for takingaction to help pollinators such as planting pollen- andnectar-rich flower strips in field margins.

— Conserving semi-natural areas.— Allowing hedgerows to flower throughout the spring and

summer.— Planting tree species that produce an abundance of

nectar and pollen in spring and summer. — Minimising use of pesticides by employing technological

solutions to target application only when it is needed.— Employing integrated pest management schemes to

target pesticide use or use alternative biocontrols.— Selecting longer crop rotations that create more complex

landscapes and require less chemical control of pests.— Providing a mix of different habitats such as grassland,

scrubland, woodland, bare ground, hedgerows, dead

wood and watercourses where possible to encourage adiversity of pollinators.

The public can help by: — Pollinator-friendly gardening, planting a range of cottage-

garden and native flowers that bloom over the season. — Choosing flowering plants that provide nectar and pollen.— Growing flowers of different shapes and sizes (eg open

flowers, tubular flowers) that will attract a diversity ofdifferent pollinators.

— Cutting lawns less often to allow them to bloom withbuttercups, daisies and clovers.

— Encouraging local councils to help bees and save moneyby allowing flowers to bloom in hedgerows, road vergesand parks and cutting them less frequently over thesummer.

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